1. Field of the Invention
The present invention relates to a device and method for surgically joining severed small tubular structures.
2. The Prior Art
It is presently possible to surgically join small tubular structures, for example, severed arteries smaller than 5.0 millimeters (mm) in size, and even less than 1.0 mm in size. However, considerable surgical dexterity is required. If reunification of a patent conduit with normal or nearly normal flow is to be achieved, great pains must be taken to insure gentle handling of delicate tissues, particularly avoiding unnecessary stretching, crushing, or piercing of the tissues. Such trauma increases the likelihood of thrombosis and/or structural failure.
Anastomosis of small tubular structures is preferably performed under a microscope to aid in visualization. In the case of end-to-end anastomosis, the severed vessels are gently clamped so as to interrupt flow and to make the ends available for suture. An initial suture is installed to connect the ends together at a single point. This initial suture is usually positioned at the anatomically deepest aspect of the anastomosis, a position which is generally referred to as the "back wall" or "posterior wall" of the anastomosis. Additional sutures are then placed to join additional points of the separated ends.
A number of factors contribute to the difficulty of performing this procedure:
(a) Loss of Configuration
When tubular structures, such as blood vessels, are emptied of their pressurized contents (such as blood), the tubular lumen collapses and the tubular shape is lost. The ends of such severed, collapsed structures are difficult to visualize in their previously intact configuration or their preferably restored configuration. They are also difficult to grasp and manipulate in order to suture.
(b) Trauma from Instrumentation
In placing sutures through the vessel wall, the suture needle is passed through the wall either from outside to in or from inside to out. To facilitate passing a suture needle inward towards the lumen, an instrument, such as a small forceps, is typically inserted into the lumen in order to provide counter pressure to the thrust of the suturing needle, as well as to attempt to separate the wall being sutured from the wall behind it. Alternatively, the surgeon may be required to grasp the full thickness of the wall being sutured with a forceps in order to position it so that it may be pierced by the suturing needle. This requirement for forceps to grasp and manipulate the dissociated structures introduces an unwanted element of tissue trauma.
(c) Inadvertent Misplacement of Sutures
With tubular shapes, especially those of small diameter, the opposite wall from the point being sutured might be inadvertently pierced or traversed in the line of the thrust of the suturing needle, especially in placing sutures through the vessel wall from outside to in, toward the lumen. This is especially so because of the lumen being collapsed. Not only might tissues of the opposing wall be traumatized, but the lumen may be inadvertently sutured shut.
(d) Spasm of the Vessel
Trauma to the vessel may cause it to spasm, adding a complicating factor in performing these procedures.
(e) Time for Performance
The present methods of performing anastomoses are time consuming. Surgical risk, particularly anesthetic risk, is known to be increased with time.
(f) Operator Fatigue
The intense concentration, effort and time required by the present methods contribute to frustration and fatigue.